Method of purifying benzol



Patented May 13, 1930 UNITED STATES CHARLES FREDERICK HAeEi oF GENEVA, New YORK METHOD OF PURIFYING BENZOL No Drawing.

The present invention relates to fuels for internal combustion engines, more particularly to the production of high grade motor fuels from commercial coal tar products such for example as commercial benzol.

As is well known one form of commercial benzol is a coal tar distillate, and as a byproduct in the manufacture of illuminating gas is available in large quantities at comparatively low prices. It may be obtained at various stages during the distillation of coal tar, such as direct from the ovens, or from the drippings collected from the mains. However obtained, the initial liquid which I use has not been refined by stripping with light oils, or distillation, or by acid or alkali washes, or in any other way, and is composed principally of benzol contaminated with tarry oils in sufiicient quantity to render it unsuitable as a motor fuel. One grade of this commercial benzol as successfully used by me contains approximately 92% benzol and 8% tarry oils. It is brown in color due to the presence of tar oils, burns with a smoky flame, and when used as a motor fuel leaves gummy and undesirable deposits which rapidly clog the carburetor of an engine, and leave undesirable deposits in the engine to such an extent that the commercial benzol is wholly unfitted for use either alone, or blended with other hydrocarbon oils, for use as a motor fuel.

Various methods have heretofore been utilized to refine commercial benzol for use as a motor fuel when blended with other hydro carbon oils, including the treatment with sulphuric acid to eliminate the'impurities, and distillation at high temperature and fractional condensation of the distillate to elimi- 40 nate the undesirable constituents. Such prior methods are so expensive as to make use of the resultant product as a motor fuel without the blending, prohibitive in cost, and give an unsatisfactory product, due to failure to eliminate the heavy tars and tar oils which burn with a smoky flame leaving gummy deposits in an engine.

I have discovered by extended experiments and trial that it is possible by distillation to separate from commercial benzol a high- Application filed August 13, 1928. Serial No. 299,449.

grade motor fuel which can be utilized alone, or blended with heavier hydro-carbon oils to make high grade motor fuels that can be sold at a considerable profit in competition with the existing types of motor fuels.

Accordingly, a primary object of my invention is the production of a novel distillate of commercial benzol at comparatively low cost and which alone, or properly blended with heavier hydrocarbon oils, provides a high grade motor fuel at comparatively low cost.

Another object of the invention is the provision of novel types of motor fuels at a. cost that compares favorably with the cost of production of gasoline and high test motor fuels' A further object of the invention is the provision of novel -methods of producing high grade low cost motor fuels in efficient and economical manner.

Still further objects of the invention will appear in the following detailed description of preferred compositions, and methods of producing my improved motor fuels, and are defined by the terms of the appended claims.

My invention is based upon my discovery that when commercial benzol is distilled at a temperature of no higher than approximately 250Fahrenheit and in the range of from about 90 to 100 Fahrenheit as a lower limit, and 240 to 250 Fahrenheit as an upper limit the evolved distillate is a novel high grade motor fuel in which no undesirable tars or tar oils are present, and which either alone or properly blended with heavier hydrocarbon oils as hereinafter in detail set forth provides satisfactory and economical motor fuels.

In accordance with my preferred method of producing this improved distillate, commercial benzol is placed in a still which is preferably heated by a steam jacket in order to permit a close control. of the temperature to be had, and the heating jacket is preferably brought to a temperature approximately 240 to 250 Fahrenheit and the evolved distillate is condensed. The distillation is car ried on at this temperature until substantially no more distillate is evolved. At the completion of the distillation a free running black residue remains in the still which I term tar oil. This residue when poured into water at ordinary temperatures separate into a product heavier than water which will sink to the bottom, and a product lighter than water that rises and floats on the surface of the water. When heated to a temperature above 250 Fahrenheit to 370 Fahrenheit the lighter tar oils will distill from this residue leaving a tarry product in the still. This distillate-al-. though light in color, burns with a smoky flame and leaves a gummy residue and is unsuited for use in a motor fuel for this reason. While I prefer to distill the benzol in batch stills of any well known type at temperatures of 240 to 250 Fahrenheit, or less to insure against the distillation of the undesirable oils that burn with a smoky flame and leave a gummy deposit, in my distillation of commercial benzol I have noted that as the heating of the benzol proceeds the undesirable tar oils separate from the mixture. Initially a small amount of tar oil will accumulate at the top of the batch which will pass over in the initial distillate even when distilling at below temperatures of 240 to 250 Fahrenheit, and this initial distillate which is small in amount should preferably be discarded. After the small quantity of initial tar oils have distilled off, my improved clear colorless distillate passes over and is condensed, and as the heating proceeds the tar oils gradually form in a lower fraction of black tarry residue and tar oils. This bottom layer however, disappears as soon as the heating is discontinued and the mass in the still cools. I have observed, however, that by applying a higher heat to the still my improved distillate is at first evolved and the proportion of the lower fraction of the heavier tar oils in the still increases. If distillation with the higher temperatures is discontinued as the level of the liquid in the still approaches the lower fraction, my improved distillate useful as a satisfactory mo tor fuel will also be secured. However, if distillation at substantially higher heat applied to the still is continued after the level of said lower fraction is approached in the still the tar oils will then commence to distill and if permitted to mix in substantial quantity with the distillate firstobtained, the value of the product as a motor fuel is then destroyed. With the distillation properly carried forward the residue of what I term tar oils which form in the lower fraction in a batch still as above pointed out, will be free running and will readily drain from the still.

However, as most grades of commercial benzol contain a substantial quantity of dirt, sludge and like impurities, before distillation I prefer to wash the commercial benzol with water. This is preferably accomplished by agitating the commercial benzol with water and then permitting the agitated mixture to settle. The commercial benzol will rise to the top of the mass, and substantial quantities of the dirt, sludge, and impurities will settle to the bottom with the water, giving a cleaner product for distillation.

My improved distillate secured as above set forth by the distillation of commercial benzol can be used alone as a high grade fuel. and by my improved methods can be prod i-e l in sufliciently economical manner to per sale as an exceptionally high-grade motor rue in competition with existing types of motor fuels.

Furthermore, my improved distillate will blend with heavier oils by a simple mixing process and so blended will provide high grade motor fuels at comparatively low cost. For example, a mixture of one part of keroe sene to three parts of my improved distillate by volume provides a motor fuel equal in quality to, or better than high grade, high test, motor fuels at present sold commercially; and a mixture of one and one-half parts of kerosene to two and one-half parts of my improved distillate by volume provides a motor fuel equal in quality to the motor fuel sold as straight gasoline on the market.

A mixture of three parts of volume of my improved distillate to one part by of volume of light fuel oil provides a blended motor fuel equal in quality to good straight commercial gasoline, while reducing the proportion of fuel oil increases the quality of this fuel.

A. mixture of one part of my improved distillate to three parts of volume of low grade gasoline provides a blended motor fuel equal in quality to the high grade, high test motor fuel.

It is to be understood that when my improved distillate is blended with heavier oils such as gasoline, kerosene, fuel oils and the like, the heavier oils should be clean and free from dirt.

If dirty oils or oils containin impurities are to be blended I have found t at by mixing such oils with commercial benzol in the proper proportions as above set forth, and washing by agitating with water and permitting to settle, the heavier dirt particles and impurities will settle to the bottom with the water and the mixture of benzol and heavier'oils will rise to the top of the water. Such mixtures may then be distilled and as distillation thereof proceeds the tar oils1 separate and settle to the bottom of the stil liquid level is above the lower layer or fraction of tar oil which separates as above pointed out, is a satisfactory blended motor fuel, but distillation should be discontinued as the level of the lower fraction of black tar oils is reached or approached. As such distillation of mixtures must be carried out at higher temperatures than 240 F ahren- The distillate evolved, so long as the volume of crude oil with equal parts by volume of commercial benzol and distilling attemperatures up to 700 Fahrenheit, and preferably at from 400 Fahrenheit to 600 Fahrenheit, and stopping the distillation as the level of the liquid in the still approaches or reaches the level of the black lower fraction of tar oils which forms as the distillation proceeds, the evolved distillate is an excellent motor fuel equal in quality to the best grades of gasoline marketed.

It willaccordingly be seen that in accordance with my improved methods of producing motor fuels, commercial benzol, either alone or mixed with suitable proportions of heavier hydrocarbon oils is distilled in such manner asv to form black layers or fraction of'tar oils of free running liquid consistency in the bottom of a batch still and to carry the distillation forward below the vaporizzis ing temperature of this lower fraction which carding the residue, and collecting the evolved distillate.

2. The method of producing a clear distillate suitable as a motor fuel and substantially free from tarry oils by distillation, which comprises raising the temperature of commercial benzol containing substantial quantities of tarry oils to a temperature at which a clear distillate is evolved substan' tially free of tarry oils, discarding the distillate evolved prior to the benzol attaining the above temperature, maintaining the tem perature of the benzol as high as this temperature and below that at which said tarry oils distil over, discarding the residue, and collecting the evolved distillate.

3. The method as defined in claim 2 wherein the temperature defined is of the order of 240 F.

In testimony whereof I afiix my signature.

- CHARLES F. HAGEN.

is above 240 Fahrenheit, orto discontinue the distillation as the level of this fraction of free running tar oils is approached. The

distillate of commercial benzol evolved in. this way is a novel motor fuel that can be produced at a sufficiently low cost to be sold in competition with high test commercial motor fuels, and blended with heavier hydrocarbon oils provides high grade, low cost 85 motor fuels. It is to be noted, however, that when blending my improved distillate with the heavier oils such for example as fuel oils, kerosene and the like, the proportions of the heavier oils should not be substan- 40 tially increased above those given as such blends with substantial higher proportions of the heavier oils will not give satisfactory motor fuels.

Having described preferred embodiments of my invention only, it is to be understood that the examples given are illustrative and not restrictive, and that the scope of my invention is to be determined from the terms of the appended claims.

Accordingly, what is claimed as new and which is substantially free of tarry oils, discarding the distillate evolved prior to the mixture attaining the above temperature, maintaining the temperature of the mixture as high as this temperature and below that at which the said tarry oils distil over, dis 

